Since the steam engines of the 1800's, automotive vehicles have been driven with crank systems tending to lose about a quarter of the driving energy. This problem was recognized by Lenoir and later by Oechelhauser and Junkers who proposed the use of flying piston internal combustion engines.
From a mechanical viewpoint, however, the longitudinal energy of the flying pistons was partly lost in the conversion of this energy to the rotation energy required for the remainder of the vehicle drive. As a consequence, the earlier flying piston systems did fully not eliminate the losses of crank drives.
U.S. Pat. No. 3,510,703 discloses a system in which the mechanical energy of a fly piston internal-combustion engine is converted into electrical energy utilizing a longitudinally actuated generator and the electrical energy is then employed to operate the wheel-drive motors of a vehicle. When this system is applied as a truck drive the dimensions of the electrical part between the pistons were excessive, leading to an overall length of the apparatus which was more than desirable and a weight per unit of power output which was considerable as well.
Another disadvantage of this type of generator was that the mechanical flux exchange between the stator and the linearly displaceable armature was longitudinal rather than rotational or radially oscillating which led to a reduced efficiency.
Efforts to eliminate these drawbacks were made in German Patent 35 39 069 by providing a radially swinging generator part to opposite sides of a pair of pistons of the internal combustion machine connected by racks. It should be noted that, by comparison with machines whose pistons can be subjected to the expansion force of the exploding fuel only at one side, flying piston machines which can be fired at opposite sides of the piston assembly can have an increase in overall efficiency by some 25 to 30%.